The present invention relates to catalyst systems comprising specifically substituted metallocenes which can advantageously be used in olefin polymerization and to a process for preparing them and also to their use in the polymerization of olefins.
Processes for preparing polyolefins with the aid of soluble, homogeneous catalyst systems comprising a transition metal component of the metallocene type and a cocatalyst component such as an aluminoxane, a Lewis acid or an ionic compound are known. These catalysts have a high activity and give polymers and copolymers having a narrow molar mass distribution.
In polymerization processes using soluble, homogeneous catalyst systems, thick deposits form on reactor walls and stirrer if the polymer is obtained as a solid. These deposits are always formed by agglomeration of the polymer particles when metallocene and/or cocatalyst are present in dissolved form in the suspension. Such deposits in the reactor systems have to be removed regularly, since they rapidly reach considerable thicknesses, have a high strength and prevent heat transfer to the cooling medium. Such homogeneous catalyst systems cannot be used industrially in modern polymerization processes in liquid monomer or in the gas phase.
To avoid deposit formation in the reactor, supported catalyst systems in which the metallocene and/or the aluminum compound serving as cocatalyst are fixed to an inorganic support material have been proposed.
EP-A-0,576,970 discloses metallocenes and corresponding supported catalyst systems.
However, a frequent problem in the industrial use of supported catalyst systems is the leaching of the metallocene component from the support material, which results, for example, in undesirable deposit formation in the reactor.
It is an object of the present invention to find novel catalyst systems in which the metallocene component can be firmly fixed to the support and cannot be leached from the support material under industrially relevant polymerization conditions.
We have found that this object is achieved by catalyst systems comprising at least one specifically substituted metallocene which contains a cationic group as substituent.
The present invention provides a catalyst system comprising
a) at least one support,
b) at least one cocatalyst and
c) at least one metallocene of the formula (I) 
xe2x80x83where
M1 is a transition metal of Group 4 of the Periodic Table of the Elements, for example titanium, zirconium or hafnium, preferably zirconium,
R1 and R2 are identical or different and are each a hydrogen atom, a C1-C20 group, preferably a C1-C20-alkyl group, a C6-C14-aryl group, a C2-C20-alkenyl group, a C2-C20-alkynyl group, or a C7-C20-alkylaryl group, each of which may bear one or more identical or different halogen atoms as substituents, a halogen atom, an xe2x80x94SiMe3 group or an OSiMe3 group, particularly preferably hydrogen, methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, n-pentyl, branched pentyl, n-hexyl, branched hexyl, cyclohexyl or benzyl,
R3 are identical or different and are each a hydrogen atom or a C1-C40 group, preferably a C1-C20-alkyl group which may be substituted, in particular methyl, ethyl, trifluoroethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, pentyl, hexyl, octyl, cyclopropyl, cyclopentyl or cyclohexyl, a C6-C14-aryl group which may be substituted, for example phenyl, tolyl, xylyl, tert-butylphenyl, ethylphenyl, trifluoromethylphenyl, bis(trifluoromethyl)phenyl, methoxyphenyl, fluorophenyl, dimethylaminophenyl, trimethylammoniumphenyl iodide, dimethylsulfoniumphenyl bromide, triethylphosphoniumphenyl triflate, naphthyl, acenaphthyl, phenanthrenyl or anthracenyl, a C2-C20-alkenyl group, a C2-C20-alkynyl group, a C7-C20-alkylaryl group, a halogen atom, an SiMe3 group, an OSiMe3 group or a C1-C20-heterocyclic group which may be substituted, where the term heteroatom encompasses all elements with the exception of carbon and hydrogen and preferably refers to an atom of group 14, 15 or 16 of the Periodic Table of the Elements, and two radicals R3 may form a monocyclic or polycyclic ring system which may in turn be substituted, where at least one of the radicals R1, R2, R3 is a cationic group (xe2x80x94DEL)+Yxe2x88x92,
where
D is an atom of group 15 or 16 of the Periodic Table of the Elements, preferably nitrogen, phosphorus, oxygen or sulfur,
E are identical or different and are each a hydrogen atom, a C1-C20 group, preferably a C1-C20-alkyl group, a C6-C14-aryl group, a C2-C20-alkenyl group, a C2-C20-alkynyl group or a C7-C20-alkylaryl group, a trialkylsilyl group, a triarylsilyl group or an alkylarylsilyl group, which may each be substituted, and two radicals E may form a monocyclic or polycyclic ring system which may in turn be substituted, particularly preferably a hydrogen atom, methyl, ethyl, propyl, butyl, allyl, benzyl, methoxymethyl, benzyloxymethyl, 2-methoxyethoxymethyl, 2-trimethylsilylethoxymethyl or trimethylsilyl,
L is 3 when D is an atom of group 15 of the Periodic Table of the Elements and is 2 when D is an atom of group 16 of the Periodic Table of the Elements,
Y is halogen, C1-C10-alkylsulfonate, C1-C10-haloalkylsulfonate, C6-C20-arylsulfonate, C6-C20-haloarylsulfonate, C7-C20-alkylarylsulfonate, C1-C20-haloalkylcarboxylate, C1-C10-alkylsulfate, tetrafluoroborate, hexafluorophosphate, hexafluoroantimonate or hexafluoroarsenate, preferably chloride, bromide, iodide, triflate, mesylate, tosylate, benzenesulfonate, trifluoroacetate, methyl sulfate, tetrafluoroborate or hexafluorophosphate,
m is an integer less than or equal to 4 and greater than or equal to 1, preferably 1 or 2, particularly preferably 1,
mxe2x80x2 is an integer less than or equal to 4 and greater than or equal to 1, preferably 1 or 2, particularly preferably 1,
k is zero or 1, with the metallocene being unbridged when k=0 and the metallocene being bridged when k=1,
A is a bridge of the formula 
or xe2x95x90BR4, AlR4, xe2x80x94Sxe2x80x94, xe2x80x94SOxe2x80x94, xe2x80x94SO2xe2x80x94, xe2x95x90NR4, xe2x95x90PR4, xe2x95x90P(O)R4, o-phenylene or 2,2xe2x80x2-biphenylene, where
M2 is carbon, silicon, germanium, tin, nitrogen or phosphorus, preferably carbon, silicon or germanium, in particular carbon or silicon,
o is 1, 2, 3 or 4, preferably 1 or 2,
R4 and R5 are identical or different and are each, independently of one another, a hydrogen atom, halogen, a C1-C20 group, preferably a C1-C20-alkyl, in particular methyl, a C6-C14-aryl, in particular phenyl or naphthyl, a C1-C10-alkoxy, a C2-C10-alkenyl, a C7-C20-arylalkyl, a C7-C20-alkylaryl, a C6-C10-aryloxy, a C1-C10-fluoroalkyl, a C6-C10-haloaryl, a C2-C10-alkynyl, a C3-C20-alkylsilyl, in particular trimethylsilyl, triethylsilyl or tert-butyidimethylsilyl, a C3-C20-arylsilyl, in particular triphenylsilyl, or a C3-C20-alkylarylsilyl, in particular dimethylphenylsilyl, diphenylsilyl or diphenyl-tert-butylsilyl, and R4 and R5 may form a monocyclic or polycyclic ring system.
A is preferably dimethylsilanediyl, dimethylgermanediyl, ethylidene, methylethylidene, 1,1-dimethylethylidene, 1,2-dimethylethylidene, tetramethylethylidene, isopropylidene, phenylmethylmethylidene or diphenylmethylidene, particularly preferably dimethylsilanediyl or ethylidene.
The radicals X are identical or different and are each a hydrogen atom, a halogen atom such as fluorine, chlorine, bromine or iodine, a hydroxyl group, a C1-C10-alkyl group such as methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, hexyl or cyclohexyl, a C6-C15-aryl group such as phenyl or naphthyl, a C1-C10-alkoxy group such as methoxy, ethoxy or tert-butoxy, a C6-C15-aryloxy group or a benzyl group, preferably a chlorine atom, a fluorine atom, a methyl group or a benzyl group, particularly preferably a chlorine atom or a methyl group.
Particularly preferred metallocenes of the formula (I) have the formula (I*), 
where
M1, A, R1, k and X are as defined for formula (I) and
R6 are identical or different and are each a hydrogen atom or a C1-C40 group, preferably a C1-C20-alkyl group which may be substituted, in particular methyl, ethyl, trifluoromethyl, trifluoroethyl, n- propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, pentyl, hexyl, octyl, cyclopropyl, cyclopentyl or cyclohexyl, a C6-C14-aryl group which may be substituted, in particular phenyl, a C2-C20-alkynyl group, a C7-C20-alkylaryl group, halogen, an OR4 group, an SiR43 group, an NR42 group or an SR4 group, and two radicals R4 and R6, each or together, may form a monocyclic or polycyclic ring system which may in turn be substituted, where R4 is as defined for formula (I), and at least one of the radicals R6 bears a cationic group (xe2x80x94DEL)+Yxe2x88x92,
where D, E, L and Y are as defined for formula (I),
q is an integer less than or equal to 5 and greater than or equal to 1, preferably 1 or 2, particularly preferably 1,
qxe2x80x2 is an integer less than or equal to 5 and greater than or equal to 1, preferably 1 or 2, particularly preferably 1.
Illustrative but nonrestrictive examples of novel metallocenes of the formula (I) are:
dimethylsilanediylbis(2-methyl-4-(4xe2x80x2-trimethylammoniumphenyl)indenyl)dichlorozirconium diiodide
dimethylsilanediylbis(2-methyl-4-(4xe2x80x2-trimethylammoniumphenyl)indenyl)dichlorotitanium diiodide
dimethylsilanediylbis(2-methyl-4-(4xe2x80x2-trimethylammoniumphenyl)indenyl)dichlorohafnium diiodide
dimethylsilanediylbis(2-methyl-4-(3xe2x80x2-trimethylammoniumphenyl)indenyl)dichlorozirconium diiodide
dimethylsilanediylbis(2-methyl-4-(2xe2x80x2-trimethylammoniumphenyl)indenyl)dichlorozirconium diiodide
dimethylsilanediylbis(2-methyl-4-(3xe2x80x2,5xe2x80x2-bis(trimethylammonium)phenyl)indenyl)dichlorozirconium tetraiodide
dimethylsilanediylbis(2-methyl-4-(4xe2x80x2-trimethylammoniumnaphthyl)indenyl)dichlorozirconium diiodide
dimethylsilanediylbis(2-methyl-4-(4xe2x80x2-trimethylammoniumphenyl)indenyl)dichlorozirconium ditosylate
dimethylsilanediylbis(2-ethyl-4-(4xe2x80x2-trimethylammoniumphenyl)indenyl)dichlorozirconium ditriflate
dimethylsilanediylbis(2-methyl-4-(4xe2x80x2-dimethylammoniumphenyl)indenyl)dichlorozirconium dichloride
dimethylsilanediylbis(2-methyl-4-(4xe2x80x2-trimethylammoniumphenyl)indenyl)dichlorozirconium bistetrafluoroborate
dimethylsilanediylbis(2-methyl-4-(4xe2x80x2-N-methyl-N-pyrrolidinophenyl)indenyl)dichlorozirconium diiodide
dimethylsilanediylbis(2-methyl-4-(4xe2x80x2-dimethylammoniumphenyl)indenyl)dichlorotitanium dichloride
dimethylsilanediylbis(2-methyl-4-(4xe2x80x2-dimethyl(methoxymethyl)ammoniumphenyl)indenyl)dichlorozirconium dichloride
dimethylsilanediylbis(2-methyl-4-(4xe2x80x2-dimethyl(2xe2x80x3-methoxyethoxymethyl)ammonium phenyl)indenyl)dichlorozirconium dichloride
dimethylsilanediylbis(2-methyl-4-(4xe2x80x2-dimethyl(benzyloxymethyl)ammoniumphenyl)indenyl)dichlorozirconium dichloride
dimethylsilanediylbis(2-methyl-4-(4xe2x80x2-dimethyl-(2xe2x80x3-trimethylsilylethoxymethyl)ammoniumphenyl)indenyl)dichlorohafnium dichloride
dimethylsilanediylbis(2-methyl-4-(4xe2x80x2-dimethylbenzylammoniumphenyl)indenyl)dichlorozirconium dichloride
dimethylsilanediylbis(2-methyl-4-(4xe2x80x2-dimethylallylammoniumphenyl)indenyl)dichlorozirconium diiodide
dimethylsilanediylbis(2-methyl-4-(4xe2x80x2-triethylammoniumphenyl)indenyl)dichlorozirconium diiodide
dimethylsilanediylbis(2-ethyl-4-(4xe2x80x2-dimethyl-(2xe2x80x3-trimethylsilylethoxymethyl)ammoniumphenyl)indenyl)dichlorohafnium dichloride
dimethylsilanediylbis(2-ethyl-4-(4xe2x80x2-dimethylbenzylammoniumphenyl)indenyl)dichlorozirconium dichloride
dimethylsilanediylbis(2-ethyl-4-(4xe2x80x2-dimethylallylammoniumphenyl)indenyl)dichlorozirconium diiodide
dimethylsilanediylbis(2-ethyl-4-(4xe2x80x2-trimethylammoniumphenyl)indenyl)dichlorozirconium diiodide
dimethylsilanediylbis(2-n-butyl-4-(4xe2x80x2-trimethylammoniumphenyl)indenyl)dichlorozirconium diiodide
dimethylsilanediylbis(2-isopropyl-4-(4xe2x80x2-triethylammoniumphenyl)indenyl)dichlorozirconium dibromide
dimethylsilanediylbis(2-isobutyl-4-(4xe2x80x2-triethylammoniumphenyl)indenyl)dichlorozirconium ditriflate
dimethylsilanediylbis(2-ethyl-4-(4xe2x80x2-triethylphosphoniumphenyl)indenyl)dichlorozirconium diiodide
dimethylsilanediylbis(2-methyl-4-(4xe2x80x2-dimethylsulfoniumphenyl)indenyl)dichlorozirconium dibromide
dimethylsilanediylbis(2-ethyl-4-(4xe2x80x2-dimethylsulfoniumphenyl)indenyl)dichlorozirconium dibromide
dimethylsilanediylbis(2-methyl-4-(3xe2x80x2-dimethylsulfoniumphenyl)indenyl)dichlorozirconium dibromide
dimethylsilanediylbis(2-methyl-4-(2xe2x80x2-dimethylsulfoniumphenyl)indenyl)dichlorozirconium dibromide
dimethylsilanediylbis(2-methyl-4-(3xe2x80x2,5xe2x80x2-bis(dimethylsulfonium)phenyl)indenyl)dichlorozirconium tetrabromide
dimethylsilanediylbis(2-methyl-4-(4xe2x80x2-dibenzylsulfoniumphenyl)indenyl)dichlorozirconium dibromide
dimethylsilanediylbis(2-methyl-4-(4xe2x80x2-methyl(methoxymethyl)sulfoniumphenyl)indenyl)dichlorozirconium dichloride
dimethylsilanediylbis(2-methyl-4-(4xe2x80x2-diallylsulfoniumphenyl)indenyl)dichlorozirconium dibromide
dimethylsilanediylbis(2-methyl-4-(3xe2x80x2-diphenylethylphosphoniumphenyl)indenyl)dichlorozirconium diiodide
dimethylsilanediylbis(2-methyl-4-(3xe2x80x2-trimethylphosphoniumphenyl)indenyl)dichlorozirconium ditriflate
methylphenylsilanediylbis(2-isobutyl-4-(4xe2x80x2-triethylammoniumphenyl)indenyl)dichlorozirconium ditosylate
1,2-ethanediylbis(2-methyl-4-(3xe2x80x2-dimethylammoniumphenyl)indenyl)dichlorozirconium bistrifluoroacetate
1,2-ethanediylbis(2-methyl-4-(4xe2x80x2-dimethylsulfoniumphenyl)indenyl)dichlorozirconium dibromide
1,2-ethanediylbis(2-methyl-4-(3xe2x80x2-diphenylethylphosphoniumphenyl)indenyl)dichlorozirconium diiodide
dimethylsilanediylbis(2-methyl-5-trimethylammoniumindenyl)dichlorozirconium dichloride
dimethylsilanediylbis(2-methyl-5-trimethylphosphoniumindenyl)dichlorozirconium dichloride
1,2-ethanediylbis(2-methyl-4-dimethylbenzy,ammoniumindenyl)dichlorozirconium dibromide
1,2-ethanediylbis(2-methyl-4-phenyl-5-dimethylbenzylammoniumindenyl)dichlorozirconium dibromide
dimethylsilanediylbis(2-methyl-4-phenyl-6-trimethylammoniumindenyl)dichlorozirconium dichloride
dimethylsilanediylbis(2-methyl-5-dimethylsulfoniumindenyl)dichlorozirconium dibromide
dimethylsilanediylbis(2-methyl-4-(4xe2x80x2-(2xe2x80x3-trimethylammoniumethyl)phenylindenyl)dichlorozirconium dichloride
dimethylsilanediylbis(2-methyl-4-(4xe2x80x2-(3xe2x80x3-dimethylsulfoniumpropyl)phenylindenyl)dichlorozirconium diiodide
dimethylsilanediylbis(2-methyl-4-(3xe2x80x2-(2xe2x80x3-trimethylammoniumethyl)phenylindenyl)dichlorozirconium dichloride
dimethylsilanediylbis(2-methyl-4-(2xe2x80x2-trimethylammoniumethyl)indenyl)dichlorozirconium dichloride
dimethylsilanediylbis(2-(2xe2x80x2-trimethylammoniumethyl)indenyl)dichlorozirconium dichloride
dimethylsilanediylbis(2-(2xe2x80x2-trimethylammoniumethyl)-4-phenylindenyl)dichlorozirconium dibromide
dimethylsilanediylbis(2-(2xe2x80x2-dimethylsulfoniumethyl)-4,6-dimethylindenyl)dichlorozirconium diiodide
The catalyst system of the present invention comprises at least one cocatalyst (component b). The cocatalyst component which may, according to the present invention, be present in the catalyst system comprises at least one compound such as an aluminoxane or a Lewis acid or an ionic compound which reacts with a metallocene to convert it into a cationic compound.
As aluminoxane, preference is given to using a compound of the formula II
(R AlO)pxe2x80x83xe2x80x83(II).
Aluminoxanes may be, for example, cyclic as in formula (III) 
or linear as in formula (IV) 
or of the cluster type as in formula (V), as are described in the literature (JACS 117 (1995), 6465-74, Organometallics 13 (1994), 2957-2969).
The radicals R in the formulae (II), (III), (IV) and (V) may be identical or different and may be a C1-C20-hydrocarbon group preferably a C1-C6-alkyl group, a C6-C18-aryl group or benzyl, or hydrogen, and p is an integer from 2 to 50, preferably from 10 to 35.
The radicals R are preferably identical and are methyl, isobutyl, n-butyl, phenyl or benzyl, particularly preferably methyl.
If the radicals R are different, they are preferably methyl and hydrogen, methyl and isobutyl or methyl and n-butyl, where hydrogen or isobutyl or n-butyl are preferably present in a proportion of 0.01-40% (number of radicals R).
The aluminoxane can be prepared in various ways by known methods. One of the methods is, for example, reacting an aluminum-hydrocarbon compound and/or a hydridoaluminum-hydrocarbon compound with water (gaseous, solid, liquid or bound-for example as water of crystallization) in an inert solvent (e.g. toluene). To prepare an aluminoxane having different alkyl groups R, two different trialkylaluminums (AlR3 +AlRxe2x80x23) corresponding to the desired composition and reactivity are reacted with water (cf. S. Pasynkiewicz, Polyhedron 9 (1990) 429 and EP-A-0,302,424).
Regardless of the method of preparation, all aluminoxane solutions have a variable content of unreacted aluminum starting compound which is present in free form or as adduct.
As Lewis acid, preference is given to using at least one organoboron or organoaluminum compound containing C1-C20 groups such as branched or unbranched alkyl or haloalkyl, e.g. methyl, propyl, isopropyl, isobutyl or trifluoromethyl, unsaturated groups such as aryl or haloaryl, e.g. phenyl, tolyl, benzyl, p-fluorophenyl, 3,5-difluorophenyl, pentachlorophenyl, pentafluorophenyl, 3,4,5-trifluorophenyl or 3,5-di(trifluoromethyl)phenyl.
Examples of Lewis acids are trimethylaluminum, triethylaluminum, triisobutylaluminum, tributylaluminum, trifluoroborane, triphenylborane, tris(4-fluorophenyl)borane, tris(3,5-difluorophenyl)borane, tris(4-fluoromethylphenyl)borane, tris(pentafluorophenyl) borane, tris(tolyl)borane, tris(3,5-dimethylphenyl)borane, tris(3,5-difluorophenyl)borane and/or tris(3,4,5-trifluorophenyl)borane. Very particular preference is given to tris(pentafluorophenyl)borane.
As ionic cocatalysts, preference is given to using compounds which contain a noncoordinating anion, for example tetrakis(pentafluorophenyl)borates, tetraphenylborates, SbF6xe2x80x94, CF3SO3xe2x80x94 or ClO4xe2x80x94. As cationic counterion, use is made of Lewis bases such as methylamine, aniline, dimethylamine, diethylamine, N-methylaniline, diphenylamine, N,N-dimethylaniline, trimethylamine, triethylamine, tri-n-butylamine, methyidiphenylamine, pyridine, p-bromo-N,N-dimethylaniline, p-nitro-N,N-dimethylaniline, triethylphosphine, triphenylphosphine, diphenylphosphine, tetrahydrothiophene and triphenylcarbenium.
Examples of such ionic compounds which can be used according to the invention are
triethylammonium tetra(phenyl)borate
tributylammonium tetra(phenyl)borate
trimethylammonium tetra(tolyl)borate
tributylammonium tetra(tolyl)borate
tributylammonium tetra(pentafluorophenyl)borate
tributylammonium tetra(pentafluorophenyl)aluminate
tripropylammonium tetra(dimethylphenyl)borate
tributylammonium tetra(trifluoromethylphenyl)borate
tributylammonium tetra(4-fluorophenyl)aborate
N,N-dimethylanilinium tetra(phenyl)borate
N,N-diethylanilinium tetra(phenyl)borate
N,N-dimethylanilinium tetrakis(pentafluorophenyl)borate
N,N-dimethylanilinium tetrakis(pentafluorophenyl)aluminate
di(propyl)ammonium tetrakis(pentafluorophenyl)borate
di(cyclohexyl)ammonium tetrakis(pentafluorophenyl)borate
triphenylphosphonium tetrakis(phenyl)borate
triethylphosphonium tetrakis(phenyl)borate
diphenylphosphonium tetrakis(phenyl)borate
tri(methylphenyl)phosphonium tetrakis(phenyl)borate
tri(dimethylphenyl)phosphonium tetrakis(phenyl)borate
triphenylcarbenium tetrakis(pentafluorophenyl)borate
triphenylcarbenium tetrakis(pentafluorophenyl)aluminate
triphenylcarbenium tetrakis(phenyl)aluminate
ferrocenium tetrakis(pentafluorophenyl)borate and/or
ferrocenium tetrakis(pentafluorophenyl)aluminate.
Preference is given to triphenylcarbenium tetrakis(pentafluorophenyl)borate and/or N,N-dimethylanilinium tetrakis(pentafluorophenyl)borate.
It is also possible to use mixtures of at least one Lewis acid and at least one ionic compound.
Cocatalyst components which are likewise of importance are borane or carborane compounds such as
7,8-dicarbaundecaborane(13),
undecahydrido-7,8-dimethyl-7,8-dicarbaundecaborane,
dodecahydrido-1-phenyl-1,3-dicarbanonaborane,
tri(butyl)ammonium undecahydrido-8-ethyl-7,9-dicarbaundecaborate,
4-carbanonaborane(1 4),
bis(tri(butyl)ammonium) nonaborate,
bis(tri(butyl)ammonium) undecaborate,
bis(tri(butyl)ammonium) dodecaborate,
bis(tri(butyl)ammonium) decachlorodecaborate,
tri(butyl)ammonium 1-carbadecaborate,
tri(butyl)ammonium 1-carbadodecaborate,
tri(butyl)ammonium 1-trimethylsilyl-1-carbadecaborate,
tri(butyl)ammonium bis(nonahydrido-1,3-dicarbanonaborato)cobaltate(III),
tri(butyl)ammonium bis(undecahydrido-7,8-dicarbaundecaborato)ferrate(III).
The support component (component a) of the catalyst system of the present invention can be any organic or inorganic, inert solid, preferably a porous support such as talc, inorganic oxides and finely divided polymer powders (e.g. polyolefins).
Suitable inorganic oxides may be found among the oxides of elements of groups 2, 3, 4, 5, 13, 14, 15 and 16 of the Periodic Table of the Elements. Examples of oxides preferred as supports include silicon dioxide, aluminum oxide and also mixed oxides of the two elements and corresponding oxide mixtures. Other inorganic oxides which can be used alone or in combination with the abovementioned preferred oxidic supports are, for example, MgO, ZrO2, TiO2 or B2O3, to name only a few.
The support materials used have a specific surface area in the range from 10 to 1000 m2/g, a pore volume in the range from 0.1to 5 ml/g and a mean particle size from 1to 500 xcexcm. Preference is given to supports having a specific surface area in the range from 50 to 500 xcexcm, a pore volume in the range from 0.5 to 3.5 ml/g and a mean particle size in the range from 5 to 350 xcexcm. Particular preference is given to supports having a specific surface area in the range from 200 to 400 m2/g, a pore volume in the range from 0.8 to 3.0 ml/g and a mean particle size of from 10 to 200 xcexcm.
If the support material used naturally has a low moisture content or residual solvent content, dehydration or drying before use can be omitted. If this is not the case, as when using silica gel as support material, dehydration or drying is advisable. Thermal dehydration or drying of the support material can be carried out under reduced pressure and simultaneous inert gas blanketing (e.g. nitrogen). The drying temperature is in the range from 100 to 1000xc2x0 C., preferably from 200 to 800xc2x0 C. The parameter pressure is not critical in this case. The duration of the drying process can be from 1 to 24 hours. Shorter or longer drying times are possible, provided that equilibrium with the hydroxyl groups on the support surface can be established under the conditions chosen, which normally takes from 4 to 8 hours.
The support material can also be dehydrated or dried by chemical means, by reacting the adsorbed water and the hydroxyl groups on the surface with suitable passivating agents. Reaction with the passivating reagent can convert all or some of the hydroxyl groups into a form which leads to no negative interaction with the catalytically active centers. Suitable passivating agents are, for example, silicon halides and silanes, e.g. silicon tetrachloride, chlorotrimethylsilane, dimethylaminotrichlorosilane, or organometallic compounds of aluminum, boron and magnesium, for example trimethylaluminum, triethylaluminum, triisobutylaluminum, triethylborane, dibutylmagnesium. Chemical dehydration or passivation of the support material is carried out, for example, by reacting a suspension of the support material in a suitable solvent with the passivating reagent in pure form or as a solution in a suitable solvent with exclusion of air and moisture. Suitable solvents are, for example, aliphatic or aromatic hydrocarbons such as pentane, hexane, heptane, toluene or xylene. Passivation is carried out at from 25xc2x0 C. to 120xc2x0 C., preferably from 50 to 70xc2x0 C. Higher and lower temperatures are possible. The reaction time is from 30 minutes to 20 hours, preferably from 1 to 5 hours. After chemical dehydration is complete, the support material is isolated by filtration under inert conditions, washed one or more times with suitable inert solvents as have been described above and subsequently dried in a stream of inert gas or under reduced pressure.
Organic support materials such as finely divided polyolefin powders (e.g. polyethylene, polypropylene or polystyrene) can also be used and should likewise be freed of adhering moisture, solvent residues or other impurities by appropriate purification and drying operations before use.
The metallocenes used according to the present invention can be obtained by reacting a metallocene of the formula (Ia) with a reagent EY. 
The radicals R1, R2, R3, A, M1, X, E, Y, k, m and mxe2x80x2 are defined as for formula (I), and R7 are identical or different and are each a hydrogen atom or a C1-C40 group, for example a C1-C20-alkyl group which may be substituted, for example methyl, ethyl, trifluoroethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, pentyl, hexyl, octyl, cyclopropyl, cyclopentyl or cyclohexyl, a C6-C14-aryl group which may be substituted, for example phenyl, tolyl, xylyl, tert-butylphenyl, ethylphenyl, trifluoromethylphenyl, bis(trifluoromethyl)phenyl, methoxyphenyl, fluorophenyl, dimethylaminophenyl, methylthiophenyl, diethylphosphinophenyl, naphthyl, acenaphthyl, phenanthrenyl or anthracenyl, a C2-C20-alkenyl group, a C2-C20-alkynyl group, a C7-C20-alkylaryl group, a halogen atom, an SiMe3 group, an OSiMe3 group or a C1-C20-heterocyclic group, which may be substituted, where the term heteroatom refers to all elements with the exception of carbon and hydrogen and is preferably an atom of group 14, 15 or 16 of the Periodic Table of the Elements, and two radicals R7 may form a monocyclic or polycyclic ring system which may in turn be substituted, and in the metallocenes of the formula (Ia), at least one of the radicals R1, R2, R7 bears or is a group DELxe2x88x921, where D is an atom of group 15 or 16 of the Periodic Table of the Elements, in particular nitrogen, phosphorus, oxygen or sulfur, and E and L are as defined for formula (I).
Metallocenes of the formula (Ia) are prepared by methods known from the literature (e.g. EP 576 970 A1; Chem. Left., 1991, 11, p.2047 ff; Journal of Organometallic Chem., 288 (1985) 63-67 and documents cited there).
The reagent EY is a compound capable of transferring a radical E, where E and Y are as defined for formula (I).
Illustrative but nonrestrictive examples of the reagent EY are: methyl iodide, methyl bromide, methyl chloride, methyl triflate, methyl trifluoroacetate, methyl methanesulfonate, methyl p-toluenesulfonate, dimethyl sulfate, trimethyloxonium tetrafluoroborate, trimethyloxonium hexafluorophosphate, ethyl iodide, ethyl bromide, ethyl chloride, triethyloxonium tetrafluoroborate, triethyloxonium hexafluorophosphate, propyl iodide, propyl bromide, propyl triflate, butyl bromide, butyl iodide, butyl chloride, pentyl bromide, octyl bromide, benzyl chloride, benzyl bromide, benzyl triflate, allyl bromide, allyl chloride, p-methoxybenzyl chloride, trimethylsilyl chloride, trimethylsilyl bromide, trimethylsilyl iodide, trimethylsilyl triflate, tert-butyldimethylsilyl chloride, tert-butyidimethylsilyl triflate, triphenylsilyl chloride, triphenylsilyl iodide, triphenylsilyl triflate, methoxymethyl chloride (MOMCl), 2-methoxyethoxymethyl chloride (MEMCl), 2-trimethylsilylethoxymethyl chloride (SEMCl), benzyloxymethyl chloride (BOMCl), hydrogen fluoride, hydrogen chloride, hydrogen bromide, hydrogen iodide, trifluoroacetic acid, methanesulfonic acid, trifluoromethanesulfonic acid, p-toluenesulfonic acid, sulfuric acid, perchloric acid, acetic acid, triethylamine hydrochloride, trimethylamine hydrofluoride, tetrafluoroboric acid diethyl etherate and hexafluorophosphoric acid.
The process of the present invention can be carried out in the presence of a suitable solvent or in bulk. Nonrestrictive examples of suitable solvents are hydrocarbons which may be halogenated, e.g. benzene, toluene, xylene, mesitylene, ethylbenzene, chlorobenzene, dichlorobenzene, fluorobenzene, decalin, pentane, hexane, cyclohexane, dichloromethane, chloroform, tetrachloromethane, 1,2-dichloroethane or trichloroethylene, ethers such as diethyl ether, di-n-butyl ether, MTBE, THF, DME, anisole, triglyme or dioxane, amides such as DMF, dimethylacetamide or NMP, sulfoxides such as DMSO, phosphoramides such as hexamethylphosphoramide, urea derivatives such as DMPU, ketones such as acetone or ethyl methyl ketone, esters such as ethyl acetate, nitriles such as acetonitrile and also any mixtures of these.
The process of the present invention is generally carried out at from xe2x88x92100xc2x0 C. to +500xc2x0 C., preferably from xe2x88x9278xc2x0 C. to +200xc2x0 C., particularly preferably from 0xc2x0 C. to 100xc2x0 C.
The reaction can be carried out in a single-phase system or in a multiphase system.
The molar ratio of reagent EY to metallocene (Ia) is generally in the range from 0.5 to 100, preferably from 1 to 10.
The concentration of metallocene (Ia) or of reagent EY in the reaction mixture is generally in the range from 0.001 mol/l to 8 mol/l, preferably in the range from 0.01 to 3 mol/l, particularly preferably in the range from 0.1 mol/l to 2 mol/l.
The duration of the reaction of metallocenes of the formula (Ia) with a reagent EY is generally in the range from 5 minutes to 1 week, preferably in the range from 15 minutes to 48 hours.
The catalyst system of the present invention may, if desired, further comprise additional additive components. It is also possible to use mixtures of two or more metallocene compounds of the formula (I) or mixtures of metallocene compounds of the formula (I) with other metallocenes or semisandwich compounds, e.g. for preparing polyolefins having a broad or multimodal molar mass distribution.
The catalyst system of the present invention is prepared by mixing at least one metallocene of the formula (I), at least one cocatalyst and at least one passivated support.
To prepare the supported catalyst system, at least one of the above-described metallocene components in a suitable solvent is brought into contact with at least one cocatalyst component, preferably giving a soluble reaction product, an adduct or a mixture.
The composition obtained in this way is then mixed with the dehydrated or passivated support material, the solvent is removed and the resulting supported metallocene catalyst system is dried to ensure that the solvent is completely or mostly removed from the pores of the support material. The supported catalyst is obtained as a free-flowing powder.
A process for preparing a free-flowing and, if desired, prepolymerized supported catalyst system comprises the following steps:
a) Preparation of a metallocene/cocatalyst mixture in a suitable solvent or suspension medium, where the metallocene component has one of the above-described structures,
b) Application of the metallocene/cocatalyst mixture to a porous, preferably inorganic dehydrated support,
c) Removal of the major part of the solvent from the resulting mixture,
d) Isolation of the supported catalyst system,
e) If desired, prepolymerization of the supported catalyst system obtained using one or more olefinic monomer(s) in order to obtain a prepolymerized supported catalyst system.
Preferred solvents for the preparation of the metallocene/cocatalyst mixture are hydrocarbons and hydrocarbon mixtures which are liquid at the reaction temperature chosen and in which the individual components preferably dissolve. However, the solubility of the individual components is not a prerequisite, as long as it is ensured that the reaction product of metallocene and cocatalyst component is soluble in the solvent chosen. Examples of suitable solvents include alkanes such as pentane, isopentane, hexane, heptane, octane and nonane; cycloalkanes such as cyclopentane and cyclohexane; and aromatics such as benzene, toluene, ethylbenzene and diethylbenzene. Very particular preference is given to toluene.
The amounts of aluminoxane and metallocene used in the preparation of the supported catalyst system can be varied over a wide range. Preference is given to setting a molar ratio of aluminum to transition metal in the metallocene of from 10:1 to 1000:1, very particularly preferably from 50:1 to 500:1. In the case of methylaluminoxane, preference is given to using 30% strength solutions in toluene, but the use of 10% strength solutions is also possible.
For preactivation, the metallocene in the form of a solid is dissolved in a solution of the aluminoxane in a suitable solvent. It is also possible to dissolve the metallocene separately in a suitable solvent and subsequently to combine this solution with the aluminoxane solution. Preference is given to using toluene.
The preactivation time is from 1 minute to 200 hours.
The preactivation can take place at room temperature (25xc2x0 C.). The use of higher temperatures may in some cases shorten the preactivation time required and effect an additional increase in the activity. In this case, higher temperature means a temperature in the range from 50 to 100xc2x0 C.
The preactivated solution or the metallocene/cocatalyst mixture is subsequently combined with an inert support material, usually silica gel, which is in the form of a dry powder or as a suspension in one of the abovementioned solvents. The support material is preferably used as powder. The order of addition is immaterial. The preactivated metallocene/cocatalyst solution or the metallocene/cocatalyst mixture can be added to the support material, or else the support material can be introduced into the solution.
The volume of the preactivated solution or the metallocene/cocatalyst mixture can exceed 100% of the total pore volume of the support material used or else can be up to 100% of the total pore volume.
The temperature at which the preactivated solution or the metallocene/cocatalyst mixture is brought into contact with the support material can vary in a range from 0 to 100xc2x0 C. However, lower or higher temperatures are also possible.
Subsequently, the solvent is completely or mostly removed from the supported catalyst system, during which the mixture can be stirred and, if desired, also heated. Preference is given to removing both the visible proportion of the solvent and also the proportion in the pores of the support material. Removal of the solvent can be carried out in a conventional way using reduced pressure and/or flushing with inert gas. In the drying procedure, the mixture can be heated until the free solvent has been removed, which usually takes from 1 to 3 hours at a preferably selected temperature in the range from 30 to 60xc2x0 C. The free solvent is the visible proportion of solvent in the mixture. For the purposes of the present invention, residual solvent is the proportion which is enclosed in the pores.
As an alternative to complete removal of the solvent, the supported catalyst system can also be dried only to a certain residual solvent content, with the free solvent having been completely removed. The supported catalyst system can subsequently be washed with a low-boiling hydrocarbon such as pentane or hexane and dried again.
The supported catalyst system prepared according to the present invention can either be used directly for the polymerization of olefins or be prepolymerized using one or more olefinic monomers before use in a polymerization process. The prepolymerization procedure for supported catalyst systems is described, for example, in WO 94/28034.
As additive, a small amount of olefin, preferably an xcex1-olefin (for example styrene or phenyldimethylvinylsilane), as activity-increasing component or, for example, an antistatic (as described in U.S. Ser. No. 08/365280) can be added during or after the preparation of the supported catalyst system. The molar ratio of additive to metallocene component compound I is preferably from 1:1000 to 1000:1, very particularly preferably from 1:20 to 20:1.
The present invention also describes a process for preparing a polyolefin by polymerization of one or more olefins in the presence of the catalyst system of the present invention comprising at least one transition metal component of the formula (I). For the purposes of the present invention, the term polymerization encompasses both homopolymerization and copolymerization.
Preference is given to polymerizing olefins of the formula Rmxe2x80x94CHxe2x95x90CHxe2x80x94Rn, where Rm and Rn are identical or different and are each a hydrogen atom or an organic radical having from 1 to 20 carbon atoms, in particular from 1 to 10 carbon atoms, and Rm and Rn together with the atoms connecting them can form one or more rings.
Examples of such olefins are 1-olefins having 2-40 carbon atoms, preferably from 2 to 10 carbon atoms, e.g. ethene, propene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene or 1-octene, styrene, dienes such as 1,3-butadiene, 1,4-hexadiene, vinylnorbornene, norbornadiene or ethylnorbornadiene, and cyclic olefins such as norbornene, tetracyclododecene or methylnorbornene. In the process of the present invention, preference is given to homopolymerizing propene or ethene or copolymerizing propene with ethene and/or with one or more 1-olefins having from 4 to 20 carbon atoms, e.g. hexene, and/or one or more dienes having from 4 to 20 carbon atoms, e.g. 1,4-butadiene, norbornadiene, ethylidenenorbornene or ethyinorbornadiene. Examples of such copolymers are ethene-propene copolymers or ethene-propene-1,4-hexadiene terpolymers.
The polymerization is carried out at from xe2x88x9260 to 300xc2x0 C., preferably from 50 to 200xc2x0 C., very particularly preferably 50-80xc2x0 C. The pressure is from 0.5 to 2000 bar, preferably from 5 to 64 bar.
The polymerization can be carried out in solution, in bulk, in suspension or in the gas phase, continuously or batchwise, in one or more stages.
The catalyst system prepared according to the present invention can be used as sole catalyst component for the polymerization of olefins having from 2 to 20 carbon atoms, but is preferably used in combination with at least one alkyl compound of an element of main groups I to III of the Periodic Table, e.g. an aluminum alkyl, magnesium alkyl or lithium alkyl or an aluminoxane. The alkyl compound is added to the monomer or suspension medium and serves to free the monomer of substances which can adversely affect the catalyst activity. The amount of alkyl compound added depends on the quality of the monomers used.
If necessary, hydrogen is added as molar mass regulator and/or to increase the activity.
In addition, an antistatic can be metered into the polymerization system during the polymerization, either together with or separately from the catalyst system used.
The polymers prepared using the catalyst system of the present invention display a uniform particle morphology and contain no fines. No deposits or caked material occur in the polymerization using the catalyst system of the present invention.
The catalyst system of the present invention gives polymers, e.g. polypropylene, having extraordinarily high stereospecificity and regiospecificity.
A particularly characteristic parameter for the stereospecificity and regiospecificity of polymers, in particular polypropylene, is the triad tacticity (TT) and the proportion of 2-1-inserted propene units (RI) which can both be determined from the 13C-NMR spectra.
The 13C-NMR spectra are measured at elevated temperature (365 K) in a mixture of hexachlorobutadiene and d2-tetrachloroethane. The resonance signal of d2-tetrachloroethane (xcex4=73.81 ppm) is used as internal reference for all the 13C-NMR spectra of the polypropylene samples measured.
To determine the triad tacticity of polypropylene, the methyl resonance signals in the 13C-NMR spectrum from 23 to 16 ppm are examined; cf. J. C. Randall, Polymer Sequence Determination: Carbon-13 NMR Method, Academic Press New York 1978; A. Zambelli, P. Locatelli, G. Bajo, F. A. Bovey, Macromolecules 8 (1975), 687-689; H. N. Cheng, J. A. Ewen, Makromol. Chem. 190 (1989),1931-1943. Three successive 1-2-inserted propene units whose methyl groups are arranged on the same side in the xe2x80x9cFischer Projectionxe2x80x9d are referred to as mm triads (xcex4=21.0 ppm to 22.0 ppm). If only the second methyl group of the three successive propene units points to the other side, one speaks of an rr triad (xcex4=19.5 ppm to 20.3 ppm), and if only the third methyl group of the three successive propene units points to the other side, of an mr triad (xcex4=20.3 ppm to 21.0 ppm). The triad tacticity is calculated using the following formula:
TT(%)=mm/(mm+mr+rr)xc2x7100
If a propene unit is inserted inversely into the growing polymer chain, this is referred to as a 2-1 insertion; cf. T. Tsutsui, N. Ishimaru, A. Mizuno, A. Toyota, N. Kashiwa, Polymer 30 (1989), 1350-56. The following different structural arrangements are possible: 
The proportion of 2-1-inserted propene units (RI) can be calculated using the following formula:
RI(%)=0.5Ixcex1,xcex2(Ixcex1,xcex1+Ixcex1,xcex2+Ixcex1,xcex4)xc2x7100,
where
Ixcex1,xcex1 is the sum of the intensities of the resonance signals at xcex4=41.84, 42.92 and 46.22 ppm,
Ixcex1,xcex2 is the sum of the intensities of the resonance signals at xcex4=30.13, 32.12, 35.11 and 35.57 ppm and
Ixcex1,xcex4 is the intensity of the resonance signal at xcex4=37.08 ppm.
The isotactic polypropylene which has been prepared using the catalyst system of the present invention has a proportion of 2-1-inserted propene units RI of  less than 0.5% at a triad tacticity TT greater than 98.0%, and the Mw/Mn of the polypropylene prepared according to the present invention is from 2.5 to 3.5.
The copolymers which can be prepared using the catalyst system of the present invention have a significantly higher molar mass than those of the prior art. At the same time, such copolymers can be prepared with high productivity using industrially relevant process parameters without deposit formation by using the catalyst system of the present invention.